Fluid pressure expansible drill bits



July 27, 1965 A. w. KAMMERER FLUID PRESSURE EXPANSIBLE DRILL BITS 2Sheets-Sheet 1 Filed March 19, 1963 Ffa. 1'.

INV ENTOR.

I Illlili: inll 4\ \v \\H Q C m m flu.

rroQ/vey.

July 27, 1965 A. w. KAMMERER 3,196,960

FLUID PRESSURE EXPANSIBLE DRILL BITS Filed March 19, 1963 2 Sheets-Sheet2 ZQcf/EQ PV: HHM/MERE@ INVENTOR.

United States Patent O 3,196,960 FLUID PRESSURE EXPANSEBLE DRILL BITSArcher W. Kammerer, Fullerton, Calif., assignor of one- "th to Jean K.Lamphere, Fullerton, Calif., and oneifth to Archer W. Kammerer, Er.,Houston, Tex.

Filed Mar. 19, 1963, Ser. No. 266,261 6 Claims. (6l. 17E- 267) Thepresent invention relates to rotary drill bits, and more particularly todrill bits of the expansible type capable of enlarging the diameter ofthe well bore, or milling out a portion of casing, or similar conduit,in the well bore, or both.

The retracted cutters of a rotary expansible drill bit have beenexpanded outwardly under the action of tiuid pressure, resulting frompumping tluid down through the rotary drill string, to which the bit isattached, and into or through the bit. The tluid discharges from the bitto clean and cool its cutter members and iush the cuttings to the top ofthe hole. The quanity of fluid necessary for proper removal of cuttingsfrom the well bore requires the use of tluid discharge passages or areasof such size as to prevent the development of high pressures in the bitfor effecting cutter expansion, unless comparatively large volume andpressure pumps or compressors are used. In enlarging the diameter of awell bore in a Very hard formation, or in milling through the wall ot acasing in the well bore, the absence of high cutter expansion tluidpressures renders it diiiicult to secure full cutter expansion, or makesthe securing of full cutter expansion a comparatively long and tediousprocess. Moreover, the operator at the top of the well bore may not beable to determine with certainty when full cutter expansion has beensecured, in order that he might then proceed with the imposition ofdrilling weight on the bit to enlarge the well bore, or mill awaycasing, to the desired longitudinal extent.

Accordingly, it is an object ofthe present invention to provide animproved rotary drill bit of the iiuid pressure expansible type foroperation in a well bore, in which greater iiuid pressure can bedeveloped in the bit for expanding its cutters outwardly, and in whichthe bit permits a large flow o' circulating fluid through it for thepurpose of cleaning the bit and flushing the cuttings from the wellbore.

Another object of the invention is to provide an improved rotary drillbit of the fluid pressure expansible type for operation in a well bore,in which the area of tiuid how through the bit during outward expansionof the cutters is restricted to enable an increased back pressure to bedeveloped in the bit for expanding the cutters, and in which the area ofiiuid tiow is greatly increased after full cutter expansion has beenachieved to allow a greatly increased flow of fluid through the bit. Thegreater facility for tiuid ow through the bit is accompanied by asubstantial drop of the pressure of the fluid pumped into the well bore,thereby giving the operator at the top of the well bore a definiteindication that the cutters have been expanded to their maximum extent.

A further object of the invention is to provide an expansible rotarydrill bit embodying an improved mechanism for signalling to the operatorat the top of the well bore of the fact of full cutter expansion.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. lt will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is 3,196,966 Patented July 27, 1965 ice not to betaken in a limiting sense, since the scope of the invention is bestdefined by the appended claims.

Referring to the drawings:

FIGURE 1 is a longitudinal section through a rotary expansible drillbit, such as a milling tool, disposed within a well casing, with thecutter and other parts occupying an initial rectracted position;

FIG. 2 is an enlarged longitudinal section through a lower portion ofthe bit disclosed in FIG. l with the cutter members removed;

FIG. 3 is a longitudinal section similar to FG.V l disclosing thecutters in their fully expanded position;

FIG. 4 is an enlarged longitudinal section of the lower portion of thebit disclosed in FIG. 3 with the cutter members removed.

As shown in the drawings, a rotary expansible drill bit or milling toolA is secured to the lower end of a string of drill pipe B extending tothe top of a well bore C, and by means of which the drill bit is loweredthrough a string of well casing D to a location therein where a casingmilling operation is to commerce. In lieu of milling a casing, the drillbit could be used for enlarging the diameter of the well bore C itself.

The upper portion of the rotary drill bit consists of a mandrel havingan upper pin 11 threadedly connected to the lower end of the string ofdrill pipe B. This mandrel includes an upper kelly or drill stem member12 slidably splined to the main body 13 of the drill bit. The exteriorof the lower portion V1li of the kelly is non-circular in shape, beingtelescopically received in a companion non-circular socket 15 formed inthe main bit body 13. Speciiically, the kelly exterior and the socket 15may be of hexagonal shape to' enable the kelly 12 to be movedlongitudinally with respect to the body 13, while still being capable oftransmitting rotary motion to the body.

The mandrel l@ has a limited range of longitudinal movement within thebody, its downward movement being determined by engageemnt of the lowerend 16 of the kelly with an inwardly directed body shoulder 17, and itsupper movement being limited by engagement of an external shoulder orpiston portion 18 of the kelly with a cylinder head 19 secured to thebody. The upper end of the head has a flange 20 engaging a body shoulder21, the head being prevented from moving upwardly of the body by splitsnap retainer rings 22 fitting in a body groove 23 and overlying theflange 20. An annular guide 24 is releasably secured to the body 13 by asplit snap ring 25 above the retainer rings.

The body 13 has a plurality of expansible parts mounted on it. Theseinclude cutter supporting members 26 pivotally mounted in one or morebody slots 27 on hinge pins 23 which are suitably secured to the body toprevent their loss therefrom. Each cutter supporting member 26 dependsfrom the hinge pin 28 and carries a drag or milling cutter structure 29on its lower end.

The cutter supporting members 26 and the cutter structures 29 themselvestend to occupy a retracted position substantially entirely within thecontines of the main body 13 of the bit. These cutter supporting membersand the cutter structures are expansible outwardly to sever the casingand mill it away by operating upon the upper end E of the casingtherebelow (FIG. 3), or to enlarge the diameter of an existing wellbore. To accomplish the expansion, each cutter supporting member 26 hasan inclined expander surface 3% on its inner portion below the hinge pin28 which tapers in a downward and inward direction. Each expandersurface terminates in a lock surface 31 formed on a lock portion 32 ofthe cutter supporting member. The outward expansion is accomplished byproducing relative longitudinal movement between the mandrel 1t) and thebody 13, which will produce relative longitudinal movement betwen thecutter supporting members 26 and the tubular member 33 of the mandrel.The tubular member includes a lower portion 34 slidable within anelongate guide bushing 35 mounted in a bridge 36 secured in the body andextending across the body slot or slots 27. The guide bushing 35 `isdisposed below the lock portions 32 of the cutter supporting members 26and is secured in place by upper and lower contractible split retainerrings 35a, 35b disposed in grooves 35e in the bushing and engaging theupper and lower ends of the bridge V36.

4 Located initially substantially above the guide bushing 35 .and belowthe hinge pins 28 and in cutter supporting member recesses 37 is amandrel lock'and expander 33 which has outer surfaces 39 adapted toengage the expander surfaces 30 and the lock surfaces 31.' The lock andexpander 38 may be formed integral with the tubular member 33, the upperend of the latter beingpiloted within a socket 4G formed in the lowerportion id of the kelly 12. An enlarged boss 41 on the tubular member 33engages a downwardly facing shoulder 42 of the kelly, the tubular memberbeing held against this shoulder by a suitable split retainer orv lockring e3 snapped into an internal groove 44 encompassing the kelly socketand engaging the lower end of the tubular memberboss 41.

A gaseous fluid medium, drilling mud, or other suitable fluid can passdown through the central passage 45 in the kelly or drill stem 12 andinto the central passage (i6 extending completely through the tubularmember 33. Leakage of uid around the exterior of the tubular member 33is prevented by a suitable side seal ring 47, such as a rubber orrubber-like O ring, in a peripheral grooveV 48 in the kelly, whichengages the interior of the boss 41.

Assuming Vthe body of the tool to be elevated relatively along thetubular mandrel. 10, the inclined expander surfaces 30 of the cuttersupporting members 26 will shift upwardly `along the lock and expanderportion 3S of the tubular member 33. During such upward shifting, thecutter supporting members 26 and the cutter structures 29 carriedthereby will pivot about the hinge pins 23 and be urged in an outwarddirection. The upward movement of the body `13 with respect to themandrel 1t) can continue until the cutter structures 29 have beenshifted outwardly to their fullest extent, as determined by engagementof stop shoulders 49 on the cutter supporting members 26 with companionshoulders formed in the body'on opposite sides of the body slot or slots`27. When such engagement occurs, the lower end 16 of the kelly portion12 of the tubular mandrel will engage the body shoulder 17 and the lockand expander 3S on the tubular member 33 will be disposed behind and inengagement with the lock portions 32 of the cutter supporting members26.

It is to be noted that the surfaces 31 of the lock portions 32 of thecutter supporting members 26 and the corn-5 panion surfaces 39 on thelock and expander portion 38 of the tubular member are substantiallyparallel to the axis ofthe drill bit, when the'cutters 29 are fullyexpanded,.to prevent their reactive forces on the cutter structures 29from moving the latter inwardly. As a practical matter, it is preferredthat the coengaging lock surfaces 39, 31 be inclined slightly in adownward direction toward the axis of the tool to insure release of thelock and the expander portion 33 from the cutter supporting members 26,when the latter and the cutter structures 29 are to be shifted toretracted position.

The relative longitudinal movement between the tubular mandrel and thebody 13 of the tool is accomplished by the action of fluid pressure.Thus, the piston or enlarged portion 18 on the drill stem 12 is receivedwithin a counterbore 51 formed on the upper portion of the body of thetool.l This upper portion actually constitutes a cylinder 52 having acylindrical wall 53 extending from a lower shoulder 54 defining thebottom of the counterbore to the cylinder yhead 19.

A confined cylinder space 55 is formed between the piston portion 1S ofthe kelly, the periphery of the kelly above the piston, and the cylinder52. A suitable packing or side seal ring 56 may be provided on thepiston 18, which is adapted to slidably seal against the cylindricalwall 53 Vof the cylinder 52. Fluid is thereby prevented from passing ina downward direction between the piston and the cylinder. Similarly,fluid is prevented from passing in an upward direction out of theannular cylinder space by an inner side seal ring 5S on the cylinderhead 19 slidably and sealingly engaging the periphery of the kelly abovethe piston 1S, and also by an outer side seal ring 60 disposed in thehead 19 and sealingly engaging the cylinder wall 53.

Fluid under pressure in the string of drill pipe B and in the tubularmandrel passage 45 can be fed into the cylinder space 55 through one ormore side ports 62 establishing communication between the centralpassage 45 through the kelly and the cylinder space. Such uid underpressure is developed by restricting the flow of fluid through the kelly12 and its companion tubular member 33 by means of a flow control membermounted in the lower portion of the mandrel. As a result of suchrestriction of flow, the pumping of compressed gas or drilling mud at anadequate rate through the apparatus will build up a back pressure of uidin the passage 45, which pressure will be imposed on the fluid in thecylinder space 55, acting upon the cylinder head 19 to urge the body 13of the tool in an upward direction with respect to the tubular mandrel1@ to secure outward expansion of the cutter supporting members 26 andcutter structures 29 to their fullest extent, as above described.

As apparently disclosed in the drawings, a pair of diametrically opposedsupporting mem ers 2d and cutter structures 29 is supplied, such devicesbeing disposed substantially 130 degrees from each other. Actually, itis preferred to have a drill bit with three sets of supporting membersand cutter structures, spaced substantially degrees from each other, tosecure a smoothly running device. The two sets of supporting memberstructures, and slots 27 in which they are disposed, are shown in theinterest of simplicity of the drawings.

As shown, each cutter structure 29 forms the lower portion of the cuttersupporting member 26 and is expressly designed in the specific deviceillustrated in the drawings to sever the casing D and mill it away alonga desired length. Each cutter structure includes cutter teeth '71, theleading faces 72 of the tooth preferably being provided with a suitablehardfacing material, which extends from the lower ends 73 of the teethupwardly to a substantial extent along the tooth faces. Similarly, theouter surface 74 or face of each of the teeth may be provided withhardfacing material. Such outer tooth surfaces 74 are eective in makingan initial severing cut through the well casing D, or in initiallyenlarging the diameter of the well bore C, until the cutters 29 havebeen expanded outwardly to their fullest extent, after which it is thelower ends 73 of the cutter teeth that are operable upon the upwardlyfacing end E of the severed well casing or upon the formation shoulder Fprovided in an enlarged well bore G, to mill away the casing D, or toenlarge the diameter of the well bore C, or both, in a downwarddirection.

To insure an adequate uid pressure within the drill bit to obtainoutward expansion of the cutters 29 to their fullest extent, the flow ofiluid through the drill bit is greatly restricted. After full cutterexpansion has occurred, a greater quantity of iiuid is permitted to llowthrough the bit. As shown, the flow control member 70, which may be madeof a suitable hard material, such as tungsten carbide, is pilotedupwardly within a downwardly facing counterbore 76 in the lower end 34of the tubular member 33 of the mandrel. Below the end of the tubularmember 33, the ow control device 70 is enlarged in diameter to provide ahead '77 conforming to the internal diameter of the guide bushing 35 andcapable of sliding therealong. The ow control member 7G is secured tothe tubular member 33, as by use of welding material 78.

annesso T he flow control member has a central passage 79 of acomparatively large diameter opening upwardly into the passage 4ethrough the tubular member of the mandrel. This central passageterminates in a lower end wall Si) of the control member having a chokeorifice 31 extending therethrough communicating with the central passage79 and opening downwardly through the end wall into the body slots 27.Above the central orifice 81, the head of the flow control member hasside ports or nozzles 82 communicating with the central passage 79 andopening through the periphery or" the head 80, these side ports havingareas that are substantially greater than the area through the centraloriiice 81. The side ports 82 are circumferentially spaced from oneanother to the same extent as the cutter supporting members 26 and arealigned with the slots Z7, so that when the ports S2 of the ilow controlmember are'disposed below the guide bushing 35, the ports or nozzles candischarge fluid through the slots 27 toward the expanded cutter members29, to cool them and ush the cuttings upwardly around the drill bit Aand the drill pipe B to the top of the well bore.

When the cutters Z9 are in their retracted position, such as disclosedin FIG. l, the mandrel lll and its tubular member 33 are in an upperposition with respect to the body 13 of the tool and the guide bushing35 secured thereto, to close the side ports or nozzles 32 of the controlmember (FIGS. l, 2). As a result, all of the iluid pumped down throughthe drill string B and the mandrel passage 45, de must pass out throughthe choke orice S1 of relatively small diameter, causing a comparativelylarge back pressure to be built up in the fluid within the kelly 12,which pressure is transmitted to the lluid in the ports e2 and thecylinder space 55 for upward action on the cylinder head 19, to elevatethe body 13 and cutters 26, 29 with respect to the mandrel 1t?, thecutter structures 26, 29 moving upwardly along the expander member 3Sand shifting outwardly, as described hereinabove. During their outwardshifting, the outer portions 74 of the cutter teeth engage the casingwall and elect a cutting thereon as the drill string B and drill bit Aare rotated, the rotary motion being transmitted from the mandrel 1i) tothe body 13, and from the body to the cutter supporting members 25 andcutters 29. As the casing is milled away, the cutters 29 expandoutwardly to an additional extent under the upward force exerted by thefluid on the cylinder head 1.9 to further elevate the body 13 withrespect to the mandrel 1). As the body moves upwardly, the guide bushing35 moves upwardly with it, until full cutter expansion has occurred.When such expansion occurs, the casing D will have been completelysevered and the cutters 26, 29 will be located in their outwardposition, such as disclosed in FIG. 3.

Immediately after full cutter expansion has occurred, the body 13 andcutters 26, 29 can move upwardly suddenly along the mandrel to bring thelock portions 32 of the cutter supporting members 26 along and in fullengagement with the lock portion 38 of the tubular member, this suddenupward shifting of the body and cutter members also effecting an upwardshifting of the guide bushing 35 along the flow control member 76 andbringing the lower end of the guide bushing above the side ports ornozzles 82 of the flow control member, as disclosed in FIGS. 3 and 4.The lluid being pumped down through the string of drill pipe B, or othertubular string, and through the mandrel passages 45, 46 can nowdischarge through the central ortiice 81 and also through the nozzles82, the area of uid discharge from the mandrel being much greater thanwhen all of the liuid was required to pass downwardly through theorifice alone during outward expansion of the cutters. A much largervolume of lluid can now be pumped down through the apparatus, jettingfrom the nozzles or ports 82 toward the cutters 29 to effect theircleaning and to ilush the cuttings from the well bore itself. The suddenincrease in 6 the effective area through which uid can ow through thecontrol member 'itl is accompanied by a pronounced drop in fluidpressure readily detectable at the top of the well bore, which advisesthe operator that the cutters 29 have been expanded outwardly to theirfullest extent.

When it has been deinitely determined that the cutters 29 have beenexpanded outwardly to their fullest extent, drilling weight can beimposed through the string of drill pipe B on the mandrel 10 of thetool, such weight passing downwardly through the body shoulder 17 to thebody 13 and through the shoulders Sil to the. cutter supporting members26, and the cutters 29 themselves, the lower ends 73 of the cuttersbeing forced against the upwardly facing severed end E of the casing andalso against the formation shoulder F. Disintegration of the casing Dand of the formation can now occur as the result 0f rotation of thedrill pipe B and drill bit A, and the circulation of fluid down throughthe drill pipe and the bit, the fluid discharging from the controlmember 7l) into the well bore.

After a desired length of casing D has been milled away, or the desiredlength of hole has been enlarged in diameter, or the cutters 29 havebeen completely worn, the apparatus is removed from the well bore. Allthat need be done is to discontinue the pumping of the drill- Y inglluid through the drill pipe B and the apparatus A,

to relieve the pressure in the cylinder 52, and then elevate the drillpipe. Such elevating movement will elevate the tubular mandrel 10 withrespect to the body 13 and the cutter supporting members 26, raising thelock and expander portion 3S above the expander surfaces 3G, whereuponthe cutter supporting structures 26, 29 will drop back to theirretracted positions, such as disclosed in FIG. l. In the event thecutters 29 do not move readily to such position, an upwardly facingshoulder 90 on the tubular mandrel member 33 will engage inwardprojections 91 at the upper portions of the cutter supporting members26, effecting an upward swinging of such projections 91 about the hingepins 2S and an inward shifting of the cutter supporting members 26 andcutters 29 within the contines of the body 13. If such action stillfails to shift the cutter supporting members 26 inwardly to theirfullest extent, they will engage the casing D above and adjacent to thelocation of the initial severing cut, upon elevation of the apparatus inthe well bore, which engagement will etectively force the cuttersupporting members 26 inwardly, enabling the apparatus A to be withdrawnthrough the well casing D to the top of the well bore.

I claim:

1. In a rotary drill bit to be lowered in a well bore on a rotary drillstring: a body having a slot; cutter means in said slot carried by saidbody for expansion from a retracted position laterally outwardly of saidbody; means for expanding said cutter means laterally outwardly of saidbody, including a tubular member movable relatively longitudinally insaid body; said tubular member having a fluid passage adapted to receiveiuid from the drill string and also having first passage means andsecond passage means communicating with said passage and through whichfluid is adapted to discharge from the tubular member; means on saidbody closing said second passage means whenV said tubular memberoccupies one position in said body with said cutter means retracted andwith said rst passage means open, relative longitudinal movement of saidtubular member in said body from said one position upon expansion ofsaid cutter means shifting said second passage means to open conditionin alignment with said slot; said second passage means directing fluidthrough said slot toward said cutter means when in open condition.

2. In a rotary drill bit to be lowered in a well bore on a rotary drillstring: a body having a slot; cutter means in said slot carried by saidbody for expansion from a areas-eo retracted position laterallyoutwardly of said body; iluid actuated means responsive to the pressureof rluid pumped down the tubular string for expanding said cutter meanslaterally outwardly of said body, including a tubular member movablerelatively longitudinally in said body; sai-d tubular member having a.fluid passage adapted to receive uid from the drill string and alsohaving an orifice communicating with said passage and through whichfluid from the tubular member is adapted to discharge to provide a backpressure for action on said tluid actuated means to effect expansion ofsaid cutter means; said tubular member also having passage meanscommunicating with said passage through which luid from the tubularmember is adapted to discharge; means on said body closing said passagemeans when said tubular member occupies one position in said body withsaid cutter means retracted and with said orifice open, relativelongitudinal jmovement of said tubular member in said body from said oneposition upon expansion of said cutter means shifting said passage meansto open condition in alignment with said slot; said passage meansdirecting iluid through said slot toward said cutter means when in opencondition.

3. In a rotary drill bit to be lowered in a well bore on a rotary drillstring: a body having a slot; cutter means in said slot carried by saidbody for expansion from a retracted position laterally outwardly of saidbody, means for expanding said cutter means laterally outwardly of saidbody, including a tubular member movable relatively longitudinally insaid body and coengageable expander means on said tubular member andcutter member; guide means on said body slidably receiving said tubularmember; said expander means being disposed on one side of said guidemeans; said. tubular member having a duid passage adapted to receivefluid from the drill string and also having first passage meanscommunicating with said passage and through which uid from said tubularmembery is adapted to discharge; said tubular member having secondpassage means communicating with said passage through which iluid fromthe tubular member is adapted to discharge; said second passage meansbeing located within and closed by said guide means when said tubularmember occupies one position in said body with said cutter meansretracted and with said first passage means open, relative longitudinalmovement of said tubular member in said body from said one position uponexpansion of said cutter means shifting said second passage means fromsaid guide means to open condition at the opposite side of said guidemeans and in alignment with said'slot; said second passage meansdirecting uid through said slot toward said cutter means when in opencondition.

4. In a rotary drill bit to be lowered in a well bore on a rotary drillstring: a body having a slot; critter o means in said slot carried'bysaid body for expansion from a retracted position laterally outwardly ofsaid body; tluid actuated means responsive to the pressure of tluidpumped down the drill string for expanding said cutter means laterallyoutwardly of said body, including a tubular member movable relativelydownwardly in said body and coengageable'expander means on said tubularmember and cutter means; guide means on said body slidably receivingsaid tubular member; said expander means being disposed below said guidemeans; said tubular member having a fluid passage adapted to receivefluid from the drill string and also having an oritice communicatingwith said passage and through which uid from the tubularmember isadapted to discharge to provide a back pressure for action on said uidactuated means to etect expansion of said cutter means; said tubularmember also having passage means communicating with said passage throughwhich tluid from the tubular member is adapted to be discharged; saidpassage means being located within and close-d by said guide means whensaid tubular member occupies a relative upper position in said body withsaid cutter means retracted and with said orice open, relative downwardmovement of said tubular member in said body from said upper positionupon expansion of said cutter means shifting said passage means fromsaid guide means to open condition below said guide means and inalignment with said slot; said passage means directing 'luid throughsaid slot toward said cutter means when in open con. dition.

5. In a rotary drill bit to be lowered in a well bore:

a body having a slot; cutter means mounted on said body l in saidY slotfor expansion laterally or" said body; means for expanding and holdingsaid cutter means laterally outwardly of said body, including a mandrelconnectible to a drill string and slidably splined to said body, saidmandrel having a uid passage adapted to receive fluid from the drillstring; said mandrel having rst passage means and second passage meanscommunicating with said passage and through which tluid from the mandrelis adapted to be discharged; means on said body closing said secondpassage means when said mandrel occupies an upper position in said bodywith said cutter means retracted and with said tirst passage means open,relative downward movement of said mandrel in said body from said upperposition upon expansion of said cutter means shifting said secondpassage means to open condition in alignment with said slot; said secondpassage means directing fluid through said slot toward said cutter meanswhen in open condition.

6. ln a rotary drill bit to 4be lowered in a well bore: a bodyhaving aslot; cutter means mounted on said body in said slot for expansionlaterally of said body; means for expanding and holding said cuttermeans laterally outwardly of said body, including a mandrel connectibleto a drill string and slidably splined to said body and coengageableexpander means on said mandrel and cutter means, said mandrel having aHuid passage adapted to receive uid from the drill string; said mandrelhavl ing first passage means and second passage means communicating withsaid passage and through which duid from the mandrel is adapted to bedischarged; guide means on said body below said expander means slidablyreceiving said mandrel; said second passage means being located withinand closed by said guide means when said mandrel occupies an upperposition in said body with said cutter means retracted and with saidfirst passage means open, relative downward movement of said mandrel insaid body from said upper position upon expansion of said cutter meansshifting said second passage means'below said guide means to opencondition in alignment with said slot; said second passage meansdirecting fluid through said slot toward said cutter means when in opencondition.

References Cited by the Examiner UNITED STATES PATENTS 392,592 11/88Douglass 175-267 1,485,642 3/24 Stone 175--268 1,857,616 5/32 Baker175-269 2,049,450 8/36 Johnson 175--271 2,823,901 2/58 Kammerer 166-55.82,863,641 12/58 Kammerer 166--55-8 2,868,510 1/59 Dean l75-271 2,922,6271/60 Kammerer 166--55.8

BENJAMIN HERSH, Primary Examiner.

1. IN A ROTARY DRILL BIT TO BE LOWERED IN A WELL BORE ON A ROTARY DRILLSTRING: A BODY HAVING A SLOT; CUTTER MEANS IN SAID SLOT CARRIED BY SAIDBODY FOR EXPANSION FROM A RETRACTED POSITION LATERALLY OUTWARDLY OF SAIDBODY; MEANS FOR EXPANDING SAID CUTTER MEANS LATERALLY OUTWARDLY OF SAIDBODY, INCLUDING A TUBULAR MEMBER MOVABLE RELATIVELY LONGITUDINALLY INSAID BODY; SAID TUBULAR MEMBER HAVING A FLUID PASSAGE ADAPTED TO RECEIVEFLUID FROM THE DRILL STRING AND ALSO HAVING FIRST PASSAGE MEANS ANDSECOND PASSAGE MEANS COMMUNICATING WITH SAID PASSAGE AND THROUGH WHICHFLUID IS ADAPTED TO DISCHARGE FROM THE TUBULAR MEMBER; MEANS ON SAIDBODY CLOSING SAID SECOND PASSAGE MEANS WHEN SAID TUBULARE MEMBEROCCUPIES ONE POSITION IN SAID BODY WITH SAID CUTTER MEANS RETRACTED ANDWITH SAID FIRST PASSAGE MEANS OPEN, RELATIVE LONGITUDINAL MOVEMENT OFSAID TUBULAR MEMBER IN SAID BODY FROM SAID ONE POSITION UPON EXPANSIONOF SAID CUTTER MEANS SHIFTING SAID SECOND PASSAGE MEANS TO OPEN